Simple Robotic arm on tracks

[3nslav3]

Hi all,

This is something I started working on this morning:

My idea for this moc came from these kinds of robots:

the most important thing I wanted to recreate is the wrist at the end of the robot arm (turning, bending verticaly and horizontaly)

for the rest of the arm I used turnables instead of linear actuators (just like the real thing except for the wrist)

main specs:

5 medium pf motors

3 xl motors (2 for propulsion)

4 turnables

3 batterie boxes (counterweight and power)

4 IR receivers

what is important for me in this moc:

-the wrist

-speed of the arm!!!

-tracks for fun

-not to much wobbling

-simple!!! (no complicated mechanics)

this is still an early work in progress, the arm is able to move now, I still have to make it more solid so the arm will be able to lift things up

I'll keep you guys informed of my progress

Thank you very much for watching

update: 9-1-2012

movement video (I did not rotate the base of the robot due to a lack of an IR channel )

http://www.youtube.com/watch?v=Gd2rnb9XtQs

update: 11-1-2012

-got rid of the lowest turnable due to the "wobble" and the lack of a 9th IR chan

-replaced the gears with worm gears

New video:

http://www.youtube.com/watch?v=aYKRJbq6dMU&hd=1

Edited January 11, 2012 by 3nslav3

[Alasdair Ryan]

Interesting idea.

[Smrgol]

Thats really nice, cant wait for it to be completed and see a video of it in action

[timslegos]

Wow that looks really cool! That is certainly a very interesting idea. i cant wait to see the video either.

tim

[Burf2000]

Keep us updated mate

[3nslav3]

Thank you all for the reply's!!!

here is a short video of the movement of the arm (because you asked for it )

(I did not rotate the base of the robot due to a lack of an IR channel)

http://www.youtube.com/watch?v=Gd2rnb9XtQs

Edited January 9, 2012 by 3nslav3

[Smrgol]

Nice video.

Have you tested its ability to grip/lift anything yet?

[3nslav3]

Nice video.

Have you tested its ability to grip/lift anything yet?

yes I did, it's able to lift those big unimog wheels

i'll be adding rubbers to the claw later (maybe a different claw)

Edited January 9, 2012 by 3nslav3

[trekman]

3nslav3, do you find that the gripper loosens during rotation, or is it minimal. The reason I ask is that I have a gantry type robot on NXT motors, but I had to change the gripper mechanisim. Because I was feeding a worm drive through the turntable, which was connected to a fixed motor, it dropped its cargo as it rotated the gripper. We had to change it so that the gripper motor rotated with the gripper. Is this the case with yours?

[timslegos]

Your claw is fast! I like how fast it is because it seems like a lot of fun to play with.

tim

[3nslav3]

3nslav3, do you find that the gripper loosens during rotation, or is it minimal. The reason I ask is that I have a gantry type robot on NXT motors, but I had to change the gripper mechanisim. Because I was feeding a worm drive through the turntable, which was connected to a fixed motor, it dropped its cargo as it rotated the gripper. We had to change it so that the gripper motor rotated with the gripper. Is this the case with yours?

yes it looses grip indeed when I rotate the gripper, but I'm not planning to change it because of the length and the weight of the wrist, I would like to keep it "flexible"

do you have pics or vids of that robot?

Your claw is fast! I like how fast it is because it seems like a lot of fun to play with.

tim

It's not that fast anymore :( , I had to use worm gears to make the arm able to lift heavy loads without falling down, I tried friction pins with gears to keep the arm up at first but the friction pins warn out very fast

here is a video of the arm lifting some things:

you will notice at about halfway the video that the wrist with linear actuators can be very precise

http://www.youtube.com/watch?v=aYKRJbq6dMU&hd=1

Enjoy and Thanks for watching

[timslegos]

It's not that fast anymore :( , I had to use worm gears to make the arm able to lift heavy loads without falling down, I tried friction pins with gears to keep the arm up at first but the friction pins warn out very fast

i would STRONGLY recommend not using worm gears. With straight 8/24 gear combinations you will get a lot more torque and strength that with worm gears.

tim

[DLuders]

@ 3nslav3: Have you seen this YouTube video of NeaLucille's 6-axis Lego robotic arm? Translated from French to English, the description reads "I test here the operation of 3rd and 4th axis. Later, you will see 5th, 6th axes, as grips it."

http://www.youtube.com/watch?v=jsqBZOIVuao

[Burf2000]

Some very interest stuff on here. I thought my 3 axel arm was quite cool but I need to make something like these ones!

[Huntleyfx]

I particularly like the fact this is titled "Simple." I know that any robotics are difficult. Nice proof of concept model.

[3nslav3]

Thank you!

The arm has no complicated mechanics, the 2 main turnables for the main arm movement are driven by 2 8T gears and 2 worm gears directly from a motor,

that means that each turnable has a gear on both sides so the gears don't break while lifting heavy loads and the worm gears are used to make sure the arm doesn't fall down,

I've tried to avoid worm gears in an early build but the arm kept falling down under load :( (I've tried friction pins with 8t gears on them but they warn out fast and they don't do much good to batterie life)

every other function of the arm is driven directly by motors mounted as close as possible to the function (to avoid the usage of gears as much as possible => keeping it simple)

the arm is controlled by standard lego IR remotes, no programming is involved,

I'm very happy with the results so far, the arm is light, fast and it's a lot of fun to lift things up and move things around

next step will be dressing up with some yellow panels when I have the time

Edited January 22, 2012 by 3nslav3